libgomp/oacc-init.c

   1 /* OpenACC Runtime initialization routines
   2
   3    Copyright (C) 2013-2018 Free Software Foundation, Inc.
   4
   5    Contributed by Mentor Embedded.
   6
   7    This file is part of the GNU Offloading and Multi Processing Library
   8    (libgomp).
   9
  10    Libgomp is free software; you can redistribute it and/or modify it
  11    under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3, or (at your option)
  13    any later version.
  14
  15    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  16    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  17    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  18    more details.
  19
  20    Under Section 7 of GPL version 3, you are granted additional
  21    permissions described in the GCC Runtime Library Exception, version
  22    3.1, as published by the Free Software Foundation.
  23
  24    You should have received a copy of the GNU General Public License and
  25    a copy of the GCC Runtime Library Exception along with this program;
  26    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  27    <http://www.gnu.org/licenses/>.  */
  28
  29 #include "libgomp.h"
  30 #include "oacc-int.h"
  31 #include "openacc.h"
  32 #include <assert.h>
  33 #include <stdlib.h>
  34 #include <strings.h>
  35 #include <stdbool.h>
  36 #include <string.h>
  37
  38 /* This lock is used to protect access to cached_base_dev, dispatchers and
  39    the (abstract) initialisation state of attached offloading devices.  */
  40
  41 static gomp_mutex_t acc_device_lock;
  42
  43 /* A cached version of the dispatcher for the global "current" accelerator type,
  44    e.g. used as the default when creating new host threads.  This is the
  45    device-type equivalent of goacc_device_num (which specifies which device to
  46    use out of potentially several of the same type).  If there are several
  47    devices of a given type, this points at the first one.  */
  48
  49 static struct gomp_device_descr *cached_base_dev = NULL;
  50
  51 #if defined HAVE_TLS || defined USE_EMUTLS
  52 __thread struct goacc_thread *goacc_tls_data;
  53 #else
  54 pthread_key_t goacc_tls_key;
  55 #endif
  56 static pthread_key_t goacc_cleanup_key;
  57
  58 static struct goacc_thread *goacc_threads;
  59 static gomp_mutex_t goacc_thread_lock;
  60
  61 /* An array of dispatchers for device types, indexed by the type.  This array
  62    only references "base" devices, and other instances of the same type are
  63    found by simply indexing from each such device (which are stored linearly,
  64    grouped by device in target.c:devices).  */
  65 static struct gomp_device_descr *dispatchers[_ACC_device_hwm] = { 0 };
  66
  67 attribute_hidden void
  68 goacc_register (struct gomp_device_descr *disp)
  69 {
  70   /* Only register the 0th device here.  */
  71   if (disp->target_id != 0)
  72     return;
  73
  74   gomp_mutex_lock (&acc_device_lock);
  75
  76   assert (acc_device_type (disp->type) != acc_device_none
  77           && acc_device_type (disp->type) != acc_device_default
  78           && acc_device_type (disp->type) != acc_device_not_host);
  79   assert (!dispatchers[disp->type]);
  80   dispatchers[disp->type] = disp;
  81
  82   gomp_mutex_unlock (&acc_device_lock);
  83 }
  84
  85 /* OpenACC names some things a little differently.  */
  86
  87 static const char *
  88 get_openacc_name (const char *name)
  89 {
  90   if (strcmp (name, "nvptx") == 0)
  91     return "nvidia";
  92   else
  93     return name;
  94 }
  95
  96 static const char *
  97 name_of_acc_device_t (enum acc_device_t type)
  98 {
  99   switch (type)
 100     {
 101     case acc_device_none: return "none";
 102     case acc_device_default: return "default";
 103     case acc_device_host: return "host";
 104     case acc_device_not_host: return "not_host";
 105     case acc_device_nvidia: return "nvidia";
 106     default: gomp_fatal ("unknown device type %u", (unsigned) type);
 107     }
 108 }
 109
 110 /* ACC_DEVICE_LOCK must be held before calling this function.  If FAIL_IS_ERROR
 111    is true, this function raises an error if there are no devices of type D,
 112    otherwise it returns NULL in that case.  */
 113
 114 static struct gomp_device_descr *
 115 resolve_device (acc_device_t d, bool fail_is_error)
 116 {
 117   acc_device_t d_arg = d;
 118
 119   switch (d)
 120     {
 121     case acc_device_default:
 122       {
 123         if (goacc_device_type)
 124           {
 125             /* Lookup the named device.  */
 126             while (++d != _ACC_device_hwm)
 127               if (dispatchers[d]
 128                   && !strcasecmp (goacc_device_type,
 129                                   get_openacc_name (dispatchers[d]->name))
 130                   && dispatchers[d]->get_num_devices_func () > 0)
 131                 goto found;
 132
 133             if (fail_is_error)
 134               {
 135                 gomp_mutex_unlock (&acc_device_lock);
 136                 gomp_fatal ("device type %s not supported", goacc_device_type);
 137               }
 138             else
 139               return NULL;
 140           }
 141
 142         /* No default device specified, so start scanning for any non-host
 143            device that is available.  */
 144         d = acc_device_not_host;
 145       }
 146       /* FALLTHROUGH */
 147
 148     case acc_device_not_host:
 149       /* Find the first available device after acc_device_not_host.  */
 150       while (++d != _ACC_device_hwm)
 151         if (dispatchers[d] && dispatchers[d]->get_num_devices_func () > 0)
 152           goto found;
 153       if (d_arg == acc_device_default)
 154         {
 155           d = acc_device_host;
 156           goto found;
 157         }
 158       if (fail_is_error)
 159         {
 160           gomp_mutex_unlock (&acc_device_lock);
 161           gomp_fatal ("no device found");
 162         }
 163       else
 164         return NULL;
 165       break;
 166
 167     case acc_device_host:
 168       break;
 169
 170     default:
 171       if (d > _ACC_device_hwm)
 172         {
 173           if (fail_is_error)
 174             goto unsupported_device;
 175           else
 176             return NULL;
 177         }
 178       break;
 179     }
 180  found:
 181
 182   assert (d != acc_device_none
 183           && d != acc_device_default
 184           && d != acc_device_not_host);
 185
 186   if (dispatchers[d] == NULL && fail_is_error)
 187     {
 188     unsupported_device:
 189       gomp_mutex_unlock (&acc_device_lock);
 190       gomp_fatal ("device type %s not supported", name_of_acc_device_t (d));
 191     }
 192
 193   return dispatchers[d];
 194 }
 195
 196 /* Emit a suitable error if no device of a particular type is available, or
 197    the given device number is out-of-range.  */
 198 static void
 199 acc_dev_num_out_of_range (acc_device_t d, int ord, int ndevs)
 200 {
 201   if (ndevs == 0)
 202     gomp_fatal ("no devices of type %s available", name_of_acc_device_t (d));
 203   else
 204     gomp_fatal ("device %u out of range", ord);
 205 }
 206
 207 /* This is called when plugins have been initialized, and serves to call
 208    (indirectly) the target's device_init hook.  Calling multiple times without
 209    an intervening acc_shutdown_1 call is an error.  ACC_DEVICE_LOCK must be
 210    held before calling this function.  */
 211
 212 static struct gomp_device_descr *
 213 acc_init_1 (acc_device_t d)
 214 {
 215   struct gomp_device_descr *base_dev, *acc_dev;
 216   int ndevs;
 217
 218   base_dev = resolve_device (d, true);
 219
 220   ndevs = base_dev->get_num_devices_func ();
 221
 222   if (ndevs <= 0 || goacc_device_num >= ndevs)
 223     acc_dev_num_out_of_range (d, goacc_device_num, ndevs);
 224
 225   acc_dev = &base_dev[goacc_device_num];
 226
 227   gomp_mutex_lock (&acc_dev->lock);
 228   if (acc_dev->state == GOMP_DEVICE_INITIALIZED)
 229     {
 230       gomp_mutex_unlock (&acc_dev->lock);
 231       gomp_fatal ("device already active");
 232     }
 233
 234   gomp_init_device (acc_dev);
 235   gomp_mutex_unlock (&acc_dev->lock);
 236
 237   return base_dev;
 238 }
 239
 240 /* ACC_DEVICE_LOCK must be held before calling this function.  */
 241
 242 static void
 243 acc_shutdown_1 (acc_device_t d)
 244 {
 245   struct gomp_device_descr *base_dev;
 246   struct goacc_thread *walk;
 247   int ndevs, i;
 248   bool devices_active = false;
 249
 250   /* Get the base device for this device type.  */
 251   base_dev = resolve_device (d, true);
 252
 253   ndevs = base_dev->get_num_devices_func ();
 254
 255   /* Unload all the devices of this type that have been opened.  */
 256   for (i = 0; i < ndevs; i++)
 257     {
 258       struct gomp_device_descr *acc_dev = &base_dev[i];
 259
 260       gomp_mutex_lock (&acc_dev->lock);
 261       gomp_unload_device (acc_dev);
 262       gomp_mutex_unlock (&acc_dev->lock);
 263     }
 264
 265   gomp_mutex_lock (&goacc_thread_lock);
 266
 267   /* Free target-specific TLS data and close all devices.  */
 268   for (walk = goacc_threads; walk != NULL; walk = walk->next)
 269     {
 270       if (walk->target_tls)
 271         base_dev->openacc.destroy_thread_data_func (walk->target_tls);
 272
 273       walk->target_tls = NULL;
 274
 275       /* This would mean the user is shutting down OpenACC in the middle of an
 276          "acc data" pragma.  Likely not intentional.  */
 277       if (walk->mapped_data)
 278         {
 279           gomp_mutex_unlock (&goacc_thread_lock);
 280           gomp_fatal ("shutdown in 'acc data' region");
 281         }
 282
 283       /* Similarly, if this happens then user code has done something weird.  */
 284       if (walk->saved_bound_dev)
 285         {
 286           gomp_mutex_unlock (&goacc_thread_lock);
 287           gomp_fatal ("shutdown during host fallback");
 288         }
 289
 290       if (walk->dev)
 291         {
 292           gomp_mutex_lock (&walk->dev->lock);
 293           gomp_free_memmap (&walk->dev->mem_map);
 294           gomp_mutex_unlock (&walk->dev->lock);
 295
 296           walk->dev = NULL;
 297           walk->base_dev = NULL;
 298         }
 299     }
 300
 301   gomp_mutex_unlock (&goacc_thread_lock);
 302
 303   /* Close all the devices of this type that have been opened.  */
 304   bool ret = true;
 305   for (i = 0; i < ndevs; i++)
 306     {
 307       struct gomp_device_descr *acc_dev = &base_dev[i];
 308       gomp_mutex_lock (&acc_dev->lock);
 309       if (acc_dev->state == GOMP_DEVICE_INITIALIZED)
 310         {
 311           devices_active = true;
 312           ret &= acc_dev->fini_device_func (acc_dev->target_id);
 313           acc_dev->state = GOMP_DEVICE_UNINITIALIZED;
 314         }
 315       gomp_mutex_unlock (&acc_dev->lock);
 316     }
 317
 318   if (!ret)
 319     gomp_fatal ("device finalization failed");
 320
 321   if (!devices_active)
 322     gomp_fatal ("no device initialized");
 323 }
 324
 325 static struct goacc_thread *
 326 goacc_new_thread (void)
 327 {
 328   struct goacc_thread *thr = gomp_malloc (sizeof (struct goacc_thread));
 329
 330 #if defined HAVE_TLS || defined USE_EMUTLS
 331   goacc_tls_data = thr;
 332 #else
 333   pthread_setspecific (goacc_tls_key, thr);
 334 #endif
 335
 336   pthread_setspecific (goacc_cleanup_key, thr);
 337
 338   gomp_mutex_lock (&goacc_thread_lock);
 339   thr->next = goacc_threads;
 340   goacc_threads = thr;
 341   gomp_mutex_unlock (&goacc_thread_lock);
 342
 343   return thr;
 344 }
 345
 346 static void
 347 goacc_destroy_thread (void *data)
 348 {
 349   struct goacc_thread *thr = data, *walk, *prev;
 350
 351   gomp_mutex_lock (&goacc_thread_lock);
 352
 353   if (thr)
 354     {
 355       struct gomp_device_descr *acc_dev = thr->dev;
 356
 357       if (acc_dev && thr->target_tls)
 358         {
 359           acc_dev->openacc.destroy_thread_data_func (thr->target_tls);
 360           thr->target_tls = NULL;
 361         }
 362
 363       assert (!thr->mapped_data);
 364
 365       /* Remove from thread list.  */
 366       for (prev = NULL, walk = goacc_threads; walk;
 367            prev = walk, walk = walk->next)
 368         if (walk == thr)
 369           {
 370             if (prev == NULL)
 371               goacc_threads = walk->next;
 372             else
 373               prev->next = walk->next;
 374
 375             free (thr);
 376
 377             break;
 378           }
 379
 380       assert (walk);
 381     }
 382
 383   gomp_mutex_unlock (&goacc_thread_lock);
 384 }
 385
 386 /* Use the ORD'th device instance for the current host thread (or -1 for the
 387    current global default).  The device (and the runtime) must be initialised
 388    before calling this function.  */
 389
 390 void
 391 goacc_attach_host_thread_to_device (int ord)
 392 {
 393   struct goacc_thread *thr = goacc_thread ();
 394   struct gomp_device_descr *acc_dev = NULL, *base_dev = NULL;
 395   int num_devices;
 396
 397   if (thr && thr->dev && (thr->dev->target_id == ord || ord < 0))
 398     return;
 399
 400   if (ord < 0)
 401     ord = goacc_device_num;
 402
 403   /* Decide which type of device to use.  If the current thread has a device
 404      type already (e.g. set by acc_set_device_type), use that, else use the
 405      global default.  */
 406   if (thr && thr->base_dev)
 407     base_dev = thr->base_dev;
 408   else
 409     {
 410       assert (cached_base_dev);
 411       base_dev = cached_base_dev;
 412     }
 413
 414   num_devices = base_dev->get_num_devices_func ();
 415   if (num_devices <= 0 || ord >= num_devices)
 416     acc_dev_num_out_of_range (acc_device_type (base_dev->type), ord,
 417                               num_devices);
 418
 419   if (!thr)
 420     thr = goacc_new_thread ();
 421
 422   thr->base_dev = base_dev;
 423   thr->dev = acc_dev = &base_dev[ord];
 424   thr->saved_bound_dev = NULL;
 425   thr->mapped_data = NULL;
 426
 427   thr->target_tls
 428     = acc_dev->openacc.create_thread_data_func (ord);
 429
 430   acc_dev->openacc.async_set_async_func (acc_async_sync);
 431 }
 432
 433 /* OpenACC 2.0a (3.2.12, 3.2.13) doesn't specify whether the serialization of
 434    init/shutdown is per-process or per-thread.  We choose per-process.  */
 435
 436 void
 437 acc_init (acc_device_t d)
 438 {
 439   gomp_init_targets_once ();
 440
 441   gomp_mutex_lock (&acc_device_lock);
 442
 443   cached_base_dev = acc_init_1 (d);
 444
 445   gomp_mutex_unlock (&acc_device_lock);
 446
 447   goacc_attach_host_thread_to_device (-1);
 448 }
 449
 450 ialias (acc_init)
 451
 452 void
 453 acc_shutdown (acc_device_t d)
 454 {
 455   gomp_init_targets_once ();
 456
 457   gomp_mutex_lock (&acc_device_lock);
 458
 459   acc_shutdown_1 (d);
 460
 461   gomp_mutex_unlock (&acc_device_lock);
 462 }
 463
 464 ialias (acc_shutdown)
 465
 466 int
 467 acc_get_num_devices (acc_device_t d)
 468 {
 469   int n = 0;
 470   struct gomp_device_descr *acc_dev;
 471
 472   if (d == acc_device_none)
 473     return 0;
 474
 475   gomp_init_targets_once ();
 476
 477   gomp_mutex_lock (&acc_device_lock);
 478   acc_dev = resolve_device (d, false);
 479   gomp_mutex_unlock (&acc_device_lock);
 480
 481   if (!acc_dev)
 482     return 0;
 483
 484   n = acc_dev->get_num_devices_func ();
 485   if (n < 0)
 486     n = 0;
 487
 488   return n;
 489 }
 490
 491 ialias (acc_get_num_devices)
 492
 493 /* Set the device type for the current thread only (using the current global
 494    default device number), initialising that device if necessary.  Also set the
 495    default device type for new threads to D.  */
 496
 497 void
 498 acc_set_device_type (acc_device_t d)
 499 {
 500   struct gomp_device_descr *base_dev, *acc_dev;
 501   struct goacc_thread *thr = goacc_thread ();
 502
 503   gomp_init_targets_once ();
 504
 505   gomp_mutex_lock (&acc_device_lock);
 506
 507   cached_base_dev = base_dev = resolve_device (d, true);
 508   acc_dev = &base_dev[goacc_device_num];
 509
 510   gomp_mutex_lock (&acc_dev->lock);
 511   if (acc_dev->state == GOMP_DEVICE_UNINITIALIZED)
 512     gomp_init_device (acc_dev);
 513   gomp_mutex_unlock (&acc_dev->lock);
 514
 515   gomp_mutex_unlock (&acc_device_lock);
 516
 517   /* We're changing device type: invalidate the current thread's dev and
 518      base_dev pointers.  */
 519   if (thr && thr->base_dev != base_dev)
 520     {
 521       thr->base_dev = thr->dev = NULL;
 522       if (thr->mapped_data)
 523         gomp_fatal ("acc_set_device_type in 'acc data' region");
 524     }
 525
 526   goacc_attach_host_thread_to_device (-1);
 527 }
 528
 529 ialias (acc_set_device_type)
 530
 531 acc_device_t
 532 acc_get_device_type (void)
 533 {
 534   acc_device_t res = acc_device_none;
 535   struct gomp_device_descr *dev;
 536   struct goacc_thread *thr = goacc_thread ();
 537
 538   if (thr && thr->base_dev)
 539     res = acc_device_type (thr->base_dev->type);
 540   else
 541     {
 542       gomp_init_targets_once ();
 543
 544       gomp_mutex_lock (&acc_device_lock);
 545       dev = resolve_device (acc_device_default, true);
 546       gomp_mutex_unlock (&acc_device_lock);
 547       res = acc_device_type (dev->type);
 548     }
 549
 550   assert (res != acc_device_default
 551           && res != acc_device_not_host);
 552
 553   return res;
 554 }
 555
 556 ialias (acc_get_device_type)
 557
 558 int
 559 acc_get_device_num (acc_device_t d)
 560 {
 561   const struct gomp_device_descr *dev;
 562   struct goacc_thread *thr = goacc_thread ();
 563
 564   if (d >= _ACC_device_hwm)
 565     gomp_fatal ("unknown device type %u", (unsigned) d);
 566
 567   gomp_init_targets_once ();
 568
 569   gomp_mutex_lock (&acc_device_lock);
 570   dev = resolve_device (d, true);
 571   gomp_mutex_unlock (&acc_device_lock);
 572
 573   if (thr && thr->base_dev == dev && thr->dev)
 574     return thr->dev->target_id;
 575
 576   return goacc_device_num;
 577 }
 578
 579 ialias (acc_get_device_num)
 580
 581 void
 582 acc_set_device_num (int ord, acc_device_t d)
 583 {
 584   struct gomp_device_descr *base_dev, *acc_dev;
 585   int num_devices;
 586
 587   gomp_init_targets_once ();
 588
 589   if (ord < 0)
 590     ord = goacc_device_num;
 591
 592   if ((int) d == 0)
 593     /* Set whatever device is being used by the current host thread to use
 594        device instance ORD.  It's unclear if this is supposed to affect other
 595        host threads too (OpenACC 2.0 (3.2.4) acc_set_device_num).  */
 596     goacc_attach_host_thread_to_device (ord);
 597   else
 598     {
 599       gomp_mutex_lock (&acc_device_lock);
 600
 601       cached_base_dev = base_dev = resolve_device (d, true);
 602
 603       num_devices = base_dev->get_num_devices_func ();
 604
 605       if (num_devices <= 0 || ord >= num_devices)
 606         acc_dev_num_out_of_range (d, ord, num_devices);
 607
 608       acc_dev = &base_dev[ord];
 609
 610       gomp_mutex_lock (&acc_dev->lock);
 611       if (acc_dev->state == GOMP_DEVICE_UNINITIALIZED)
 612         gomp_init_device (acc_dev);
 613       gomp_mutex_unlock (&acc_dev->lock);
 614
 615       gomp_mutex_unlock (&acc_device_lock);
 616
 617       goacc_attach_host_thread_to_device (ord);
 618     }
 619
 620   goacc_device_num = ord;
 621 }
 622
 623 ialias (acc_set_device_num)
 624
 625 /* For -O and higher, the compiler always attempts to expand acc_on_device, but
 626    if the user disables the builtin, or calls it via a pointer, we'll need this
 627    version.
 628
 629    Compile this with optimization, so that the compiler expands
 630    this, rather than generating infinitely recursive code.  */
 631
 632 int __attribute__ ((__optimize__ ("O2")))
 633 acc_on_device (acc_device_t dev)
 634 {
 635   return __builtin_acc_on_device (dev);
 636 }
 637
 638 ialias (acc_on_device)
 639
 640 attribute_hidden void
 641 goacc_runtime_initialize (void)
 642 {
 643   gomp_mutex_init (&acc_device_lock);
 644
 645 #if !(defined HAVE_TLS || defined USE_EMUTLS)
 646   pthread_key_create (&goacc_tls_key, NULL);
 647 #endif
 648
 649   pthread_key_create (&goacc_cleanup_key, goacc_destroy_thread);
 650
 651   cached_base_dev = NULL;
 652
 653   goacc_threads = NULL;
 654   gomp_mutex_init (&goacc_thread_lock);
 655
 656   /* Initialize and register the 'host' device type.  */
 657   goacc_host_init ();
 658 }
 659
 660 /* Compiler helper functions */
 661
 662 attribute_hidden void
 663 goacc_save_and_set_bind (acc_device_t d)
 664 {
 665   struct goacc_thread *thr = goacc_thread ();
 666
 667   assert (!thr->saved_bound_dev);
 668
 669   thr->saved_bound_dev = thr->dev;
 670   thr->dev = dispatchers[d];
 671 }
 672
 673 attribute_hidden void
 674 goacc_restore_bind (void)
 675 {
 676   struct goacc_thread *thr = goacc_thread ();
 677
 678   thr->dev = thr->saved_bound_dev;
 679   thr->saved_bound_dev = NULL;
 680 }
 681
 682 /* This is called from any OpenACC support function that may need to implicitly
 683    initialize the libgomp runtime, either globally or from a new host thread.
 684    On exit "goacc_thread" will return a valid & populated thread block.  */
 685
 686 attribute_hidden void
 687 goacc_lazy_initialize (void)
 688 {
 689   struct goacc_thread *thr = goacc_thread ();
 690
 691   if (thr && thr->dev)
 692     return;
 693
 694   if (!cached_base_dev)
 695     acc_init (acc_device_default);
 696   else
 697     goacc_attach_host_thread_to_device (-1);
 698 }